1. Field of the Invention
The present invention relates to an arteriostenosis inspecting apparatus which inspects presence or absence of arteriostenosis of a living person, and an ankle-blood-pressure measuring apparatus which measures a blood-pressure of an ankle of a living subject.
2. Related Art Statement
Atherosclerosis as a sort of arteriosclerosis is a disease that lipid, in particular, cholesterol deposits on walls of arteries and thereby thickens the arterial walls. Since atherosclerosis generates stenosis of an artery and thereby decreases its diameter, it is also called arteriostenosis or arteriosclerosis obliterans. There is known an inferior-and-superior-limb-blood-pressure-index measuring apparatus which can be used for inspecting arteriostenosis, by utilizing a fact that blood pressure lowers on a distal side of a body portion having arteriostenosis. The measuring apparatus is disclosed in, e.g., Japanese Patent No. 3,140,007 or its corresponding U.S. Pat. No. 6,355,000. The disclosed measuring apparatus includes a cuff worn on an inferior limb to measure a blood pressure of the inferior limb, and a cuff worn on a superior limb to measure a blood pressure of the superior limb, calculates an inferior-and-superior-limb blood-pressure index as a ratio of one of the inferior-limb blood pressure and the superior-limb blood pressure to the other, and inspects presence or absence of arteriosclerosis based on the thus calculated index.
For example, in the case where arteriosclerosis obliterans is inspected based on an inferior-and-superior-limb blood-pressure index, the index is calculated by dividing an inferior-limb systolic blood pressure by a superior-limb systolic blood pressure and, if the thus calculated index is greater than 0.9, it is judged that arteriostenosis is absent and, if the index is not greater than 0.9, it is judged that arteriostenosis is suspected.
In the above-indicated inferior-and-superior-limb-blood-pressure-index measuring apparatus, generally, an ankle is selected as the inferior limb and a cuff is worn on the ankle. Meanwhile, an ankle has two thick arteries, i.e., an anterior tibial artery and a posterior tibial artery. There are known some cases where one of the two arteries has stenosis but the other artery does not. As explained above, blood pressure lowers on a distal side of a stenotic portion. Since, however, an ankle has two thick arteries, if only one of the two arteries has, stenosis and accordingly a blood pressure of the other artery free of stenosis does not lower, the blood pressure of the other artery is measured as a blood pressure of the ankle. Thus, even if one of the two arteries may have stenosis, a measured blood pressure of the ankle may be normal, and an inferior-and-superior-limb blood-pressure index calculated based on the measured ankle blood pressure may be normal. In this case, the inferior-and-superior-limb blood-pressure index cannot be used for finding arteriostenosis.